Various means have been utilized to provide propulsion for torpedoes. Desirably, such systems should be quiet in operation to prevent or minimize the possibility of premature detection.
Further, the system should not be depth-sensitive, that is, should be capable of operating in a single, specified fashion whether located just below the surface or substantially below the surface.
Many systems that have been proposed, particularly those utilizing steam turbines, have not met the above criteria. Typically, such systems are open cycle systems where spent or exhaust steam is vented from the torpedo during its operation. Such venting not only increases the noise level of operation, but renders the torpedo sensitive to the depth at which it is running since the back pressure resisting venting will vary proportionally to depth.
To avoid these difficulties, it is proposed to provide a closed cycle steam turbine system particularly suited as a source of propulsion for torpedoes. As implied by the term "closed cycle", the working fluid, namely water, after it exhausts from the turbine as steam, is condensed and subsequently evaporated to form additional steam for driving the turbine wheel. As a consequence, the working fluid flows throughout the closed cycle, eliminating any need for venting the same, in turn, eliminating the source of noise associated with venting and sensitivity to depth.
The difficulty with such a system is that it necessarily requires more components than an open cycle system, including at a bare minimum, a condenser for condensing the exhaust steam from the turbine wheel and a pump for delivering the condensate to the boiler.
In addition, a regenerator is desirably incorporated in the system to maximize its efficiency.
To incorporate such additional components in a torpedo without unduly enlarging its size over and above that of an otherwise identical open cycle torpedo is a considerable task.
The present invention is directed to accomplishing that task.